Pen push button



FIG. 1 is a front side bottom perspective view of a pen push buttonshowing my new design, with phantom lines depicting environmentalstructure and forming no part of the claimed design;

FIG. 2 is a front elevational view thereof which is a mirror image ofthe back and side views;

FIG. 3 is a bottom plan view thereof; and,

FIG. 4 is a top plan view thereof.

The ornamental design for a pen push button, as shown and described.